Electric switch



Jall- 1959 E. c. SLAUGHTER 2, 7

ELECTRIC SWITCH Filed March 30, 1955 INVENTOR. ELMER C. SuwqHTER mm W United States Patent 2,870,286 ELECTRIC swrrcri Elmer C. Slaughter, Piqua, Ohio, assignor to The Piqua Machine & Manufacturing Company, Pizpia, 8 bit), a corporation of Ohio Application March 30, 1955, Serial No. 497,995

8 Claims. (Cl. 200-87) This invention relates to electric switches, and more particularly to magnetic holding switches utilizing a combination of permanent and electro-magnetic forces in the control of the contact carrier.

The object of the invention is to simplify the construction as well as the means and mode of operation of electric switches, whereby such switches may not only be economically manufactured, but will be more efiicient and satisfactory in use, adaptable to a wide variety of application, and be unlikely to get out of order.

' A further object of the invention is to provide a switch of relatively high current carrying capacity requiring very light actuation forces.

A further object is to provide a switch in which such actuating forces are accurately and consistently applied over long periods of use, but which resists deterioration resulting from non-use.

Another object of the invention is to present a magnetic switch particularly adapted for use as a motor starter in which there is solved the problem of providing sufficient contact pressure to insure proper current carrying capacity under starting conditions of the motor While permitting easy opening of the switch after the period of motor operation.

A further object of the invention is to obtain substantially constant contact pressure as the contacts wear, and minimum arcing during opening and closing of the contacts.

Still another object of the invention, in a switch of the class described, is to provide for variable actuating forces on the contact carrier, the intensity of such forces being increased at the time of initial closure of the contacts and being subsequently reduced and substantially balanced for a sensitive substantially low pressure responsive opening of the contacts.

A still further object of the invention is to provide a switch of the kind described of a unitary construction and adapted to be installed in a motor housing or the like as a part of such housing.

A further object of the invention is to provide an electric switch possessing the advantageous structural features, the inherent meritorious characteristics and the mode of operation herein mentioned.

With the above primary and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawing, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviously not nesessarily the only form of embodiment of the invention,

Fig. 1 is a view in front elevation of an electric switch in accordance with the illustrated embodiment of the vention ice Fig. 2 is a view in cross section taken substantially along the line 22 of Fig. 1; V

Fig. .3 is a view of the switch of Fig. 1 in bottom plan elevation;

Fig. 4 is a fragmentary top plan view of the device as shown in Fig. 2;

Fig. 5 is a diagram of the electrical connections comprised in the switch, and controlled thereby.

Like parts are indicated by similar characters of reference throughout the several views.

Referring to the drawings, in its illustrated embodiment the switch includes a mounting plate having a peripheral series of holes 11 for installation of the switch, as upon a motor housing. Also in the mounting plate 10 is a through opening 12 in which is a bushing 13 receiving for relative sliding motion a plunger 14-. The plunger 14 projects at its opposite ends through and beyond the plate 10. In the installation of the switch assembly as seen from Fig. 2 of the drawings, the right hand side of the plate 10 faces the exterior of the motor housing and, as noted, a relatively small projecting portion of the plunger 14 is accessible for actuation by suitable manual or automatic means. The opposite side of the plate 10 presents a substantially planar surface 15 to which is fixed a block 16. A substantially U-shaped bracket 17 embraces the ends of the block 16 and is pivotally connected thereto, as by pins 18. To the bracket 17 is fixed one end of an oscillatory plate 19 serving as the support for a contact carrier assembly.

That end of the'plunge1i14 extending through and beyond the planar surface 15 is formed with a projecting portion 21 of reduced diameter joined to the main body of the plunger 14 by a shoulder 22. The reduced diameter portion 21 extends through an opening 23 in the oscillatory plate E9, the latter extending from the bracket 17 downward in substantally parallel spaced apart relation to the planar surface 15 of the mounting plate '16. Suitably attached to the plate 19 is a leaf spring 24 extending upwardly into embracing relation to a limit stud 25 and having an opening through which the reduced diameter portion of the plunger 14 projects. The construction and arrangement of parts is such as to substantially seat the spring 24 on the shoulder 22 of the plunger 14. When so arranged an axial motion of the plunger 14 to the left, as seen in Fig. 2, is effective through the spring 24 to rock the plate 19 and bracket 17 to which it is secured in a clockwise direction as viewed in the drawing or in a direction to move the main body of the plate away from the mounting plate 10. Return motion of the plunger 14 releases the plate 19 to follow such motion, which it may do under the urging of springs 26 and 27 anchored to the planar surface 15 of the plate 10 and connected to opposite side edges of the plate 19 near the bracket 17.

Also mounted on the oscillatory plate 19, beyond the point of attachment of spring 24 thereto, is a contact carrier assembly, including a transversely disposed housing 28 having an open end facing the planar surface 15 of the mounting plate ill. Slidably mounted in the housing 28 is a Contact bar 29 adapted to engage relatively stationary spaced apart contacts 31 (one shown) on respective conductors 32 and 33 disposed on an insulating strip the whole of the assembly comprising the contacts 31, the elements 32 and 33 andthe strip 34 being secured by screws 35 and 36 to the wall 15 of the plate 1%. insulating washers 37 are interposed between the respective screws 35 and 36 and the elements 32 and 33. The latter areformed with respective lugs 38 and 39 constituting points of attachment for electrical leads.

The abovementioned contact bar 29 is slidably mounted on a stud 41 and is urged outward or toward the contact 31 by a compression spring 42 interposed between the bar 29 and the closed base of the housing 28, the latter providing a mounting for the base of stud 41 which projects therethrough and carries a nut 43 thereon for adjustment purposes. The opposite end of the stud 41 is formed with a head 44 limiting outward movement of the bar 29 under the influence of spring 42. In response to the aforementioned rocking motion of the plate 19 the contact bar 29 is engaged and disengaged from the stationary contacts 31 and the spring 42, it will be understood, provides a force for variable pressure in the application of contact force of the bar 29 upon the contacts 31.

Beyond the point of attachment of the housing 28 thereto, the plate 19 mounts a screw stud 45. The stud 45 is located substantially within the outer free end of the plate 19 and together with such end is received between magnetic brackets 47 and 47' secured to and in effect a part of the magnet 46 secured to mounting plate 10. This construction provides opposing magnetic faces 48 and 49 exerting opposite directions of attraction upon the plate 19. A plate 51 on the bracket 47 carries a stud 52 which limits motion of the plate 19 in one direction, motion of the plate in the opposite direction being limited by the stud 45.

The adjustment of the studs 45 and 52 may be such as to permit the contact bar 29 to engage the contacts 31 and to be disengaged therefrom, in the one instance just before the stud 45 abuts the magnet 46 and in the other instance just before the plate 19 engages stud 52. The result, as will be seen, is that the plate 19 is effective under control of plunger 14 to substantially engage the bar 29 with the contacts 31 and immediately thereafter the magnet 46 pulls the plate 19 a further distance with a snap action. The added motion of the plate serves to positively engage the bar with the contacts. and to place the spring 42 under compression. Similarly, in the return motion of the plate 19, the plate is removed from the magnetic field of face 48 and brought into the field of face 49. Contact bar 29 is actually separated from the contacts 31 in a quick or snap acting motion initiated by the tension of spring 42 plus force exerted by plunger 14. When this exceeds the pull of magnetic face 48, plate 19 moves quickly into the field of magnetic face 49. The holding forcefor maintaining the plate 19 to the left or in open position is a function of the pull of magnetic face 49 and plunger 14 which according to the instant embodiment of the invention is held, manually or otherwise, normally in an inward or leftward position.

The force required on plunger 14 to hold the plate 19 in its leftward or open position (Fig. 2) is readily adjustable by movement of stud 52. Movement of stud 52 affects the overall influence of magnetic face 49 upon the plate 19. Likewise adjustment of stud 45 alters the forcerequired on plunger 14 to open the switch inasmuch as it affects the influence of magnetic face 43 upon plate 19.

There is mounted on the underside of the block 16, between the plunger 14 and the contact housing 28, an electromagnetic frame 53 on which is wound a coil 54. The frame 53 is U-shaped and the ends thereof are arranged in such adjacent relation to the plate 19 as to exert a relatively strong magnetic attraction upon the plate when the coil 54 is sufiiciently energized. The coil 54 is in series relation to the electrical circuit established by bridging of the contacts 31 by the bar 29. The initial surge of electrical current through the coil 54 immediately upon closing of the bridging contacts 31 sets up a high magnetic flux in the electro-magnetic device to produce a relatively powerful force holding the plate 19 in a position closing the electrical contacts. As the starting tit,

surge of current is reduced to normal levels, the electromagnetic force acting on the plate 19 is diminished. At this time, the pull of the permanent magnet 46, the reduced force of the electro-magnet and the urging of springs 26 and 27 substantially balance the pressure of the contact spring 42. Thus, even though the contacts have a high contact pressure and a high current capacity, very little pressure at the plunger 14 is necessary to open the switch. Moreover, opening of the switch is cleanly accomplished since the influence of the magnetic face 43 reduces rapidly as the plate moves away therefrom and the stored energy in the contact spring 42 provides a force to produce a high acceleration independently of the forces applied at the plunger.

It further may be pointed out that due to the use of the same permanent magnet for opposing poles, variations in the permanent magnet on account of use or nonuse become of less significance than if two magnets were used since the changes involved are uniform with regard to both the magnetic faces.

The switch of the instant invention has a unitary character and is adapted, as before noted, for installation in a motor housing where it may in effect become a part of the housing but independently removable. In this connection, it is contemplated that the switch unit should include an integral plug portion whereby as a part of the operation of installing the switch unit in the motor housing the proper electrical connections automatically are made, and as a part of the operation of detaching the switch unit from the motor housing the electrical connections automatically are discontinued.

Thus, posts 55 and 56 are set in the mounting plate 10 and support a transverse bar 57 of insulating material. On the bar 57 are mounted plug elements 58 and 59 to which are connected respective electrical leads 61 and 62.

The electrical connections and mode of operation of the switch device will largely be self evident from the foregoing description considered in connection with Figs. 1 through 4. In Fig. 5, however, the wiring connections are diagrammatically illustrated. Referring to Fig. 5, power lines 63 and 64 are joined across a motor 65 by means of the instant switch. The plug elements 58 and 59 are received in a suitable receptacle 66 in the line 64. The electrical lead 61 from plug element 58 is connected directly to one of the stationary contacts 31 of the switch. The other lead 62 is connected to the other stationary contact 31 by way of the electro-magnetic coil 54. A switch closing motion of the plate 19 places the contact bar 29 in bridging relationship to the contacts 31 thus electrically connecting the plug elements 58 and 59 and so closing a circuit through the motor 65. A switch opening motion of the plate 19 moves the bar 29 out of bridging relationship to the contacts 31 and so opens the circuit through the motor 65.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of modification in its form, proportions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

Having thus described my invention, I claim:

1. A magnetic holding switch, including a mounting plate, a contact arm in substantially parallel relation to said plate and having one end connected to said plate, the other end of said arm being movable toward and from said plate, permanent magnet means mounted on said plate and comprising oppositely disposed spaced apart magnetic faces, the said other end of said arm being received between said faces and moving into and out of the respective magnetic fields thereof during motion toward and from said plate, a contact means on said arm between the ends thereof, other and mating contact means on said plate, said contact means being engaged by biasing of said arm to one of said magnetic faces, and electric surge responsive means on said mounting plate energized upon engagement of said contact means and applying a variable force for holding said contacts engaged.

2. A magnetic holding switch according to claim 1, characterized by means for controlling the to and fro movements of said arm including spring means anchored on said plate and biasing said arm in a direction to engage said contacts, and a plunger slidably mounted in said plate operable on said arm to control its movement by said spring means and to move it against the urging of said spring means toward the other one of said magnetic faces.

3. A magnetic holding switch, including a mounting plate, a contact arm in substantially parallel relation to one side of said plate and connected thereto at its one end, the other end of said arm being an outer free end, a plunger slidably mounted in said plate and said arm and operable to move said arm about said one end, away from said plate and to control movement of said arm in the opposite direction, spring means for moving said arm in said opposite direction, permanent magnet means on said plate presenting oppositely disposed spaced apart magnetic faces between which the same free outer end of said arm extends, mating electrical contacts on said arm and on said plate biased to engage under infiuence of said spring means, and electro-magnetic means on said plate providing means responsive to Surge of current therethrough on closing of said contacts and operable when energized to apply a force for holding said mating contacts in their engaged position.

4. A magnetic holding switch according to claim 3, characterized in that said plunger at its each end extends through and beyond said plate and said arm, one end thereof being in cooperative relationship with said contact arm and the other end being accessible for Operation and control of said contact arm.

5. A magnetic holding switch according to claim 4, characterized by spring means interconnecting said plunger to said contact arm, axial motion of said plunger in one direction serving through said spring to move said arm away from said plate, said spring yielding to permit overtravel of said plunger beyond the distance required to move said arm for disengagement of said contacts.

6. A unitary magnetic variable lock switch, including a mounting plate adapted for installation in to form a part of a motor housing or the like, said plate presenting on its opposite sides internal and external surfaces, electrical plug elements stationarily installed on said internal surface, flexible electrical leads extending from said plug elements, separated electrical contacts on said mounting plate to which said flexible leads respectively are connected, an electrical contact carrier movable to bridging and non-bridging relation relatively to said contacts, a pivotal mounting for said carrier on the internal surface of said plate, and an actuator for said carrier extending through said plate, and accessible for operation from the external surface thereof.

7. A variable lock switch comprising a mounting means, a control plate, means pivotally supporting said plate to said mounting means, an operating rod slidably extending through said mounting means and having a reduced extremity extending through said plate, spring means connected to said supporting means and said plate, receiving the reduced extremity of the rod therethrough and biasing said plate outwardly of said mounting means, contact means on one end of said plate opposite said mounting means, spaced opposed mating contacts on said mounting means, biasing means connecting said plate and said mounting means to bias said contacts to a closed position overcoming said spring means thereby, permanent magnet means adjacent one end of said plate to impose a holding eifect thereon in a selective position of said plate providing closed contacts, and electromagnetic means on said mounting means and adjacent said plate, said clectro-magnetic means being responsive to a current flow therethrough to impose a further holding effect on said plate in a direction to close said contacts,

8. A variable lock switch comprising a mounting means, a control plate, means pivotally supporting said plate to said mounting means, an operating means slid ably extending through said mounting means and having a reduced extremity extending through said plate, spring means connected to said supporting means and said plate, receiving the reduced extremity of the rod therethrough and biasing said plate outwardly of said mounting means, contact means on one end of said plate opposite said mounting means, spaced opposed mating contacts on said mounting means, biasing means connecting said plate and said mounting means to bias said contacts to a closed position overcoming said spring means thereby, permanent magnet means adjacent one end of said plate to impose a holding efiect thereon in a selective position of said plate providing closed contacts, and electromagnetic means on said mounting means and adjacent said plate, said electro-magnetic means being responsive to a current flow therethrough to apply a holding force upon said contacts in their closed position through said plate, said operator means being operable on release of the holding force by said electro-magnetic means for axial movement to impart a pivotal movement to said plate in a direction to open said contacts with a snap action induced by said spring means;

References Cited in the tile of this patent UNITED STATES PATENTS 692,217 Sundh Jan. 28, 1902 1,186,770 Hallock June 13, 1916 2,111,931 Howard Mar. 22, 1938 2,292,134 Leonard Aug. 4, 1942 2,302,250 Penn Nov. 17, 1942 2,376,664 Crise May 22, 1945 2,389,592 Bucklen et al. Nov. 27, 1945 2,508,381 Frerer May 23, 1950 2,620,414 Thorsheim Dec. 2, 1952 2,648,734 Kutzler Aug. 11, 1953 2,687,518 Helman Aug. 24, 1954 2,707,215 Chinn Apr. 26, 1955 FOREIGN PATENTS 592,266 Germany Feb. 5, 1934 

